Android使用SQLite数据库的示例

SQLiteDatabase db=
SQLiteDatabase.openOrCreateDatabase(
"/data/data/" + getPackageName() + "/test.db",
 null);

public class MySqliteHelper extends SQLiteOpenHelper{

public MySqliteHelper(Context context) {
  super(context, "mysqlite.db", null, 1);
  //传入四个参数
  //第一个参数context 上下文对象
  //第二个参数mysqlite.db 数据库名称(文件名)
  //第三个参数一般为null
  //第四个参数数据库版本号，这里写1
}

@Override
public void onCreate(SQLiteDatabase db) {
  /* 数据库创建的时候会回调此方法，可以用db对象执行SQL语
   * 句，创建所需要的表
   */
}

@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
//当数据库升级时调用此方法
}
}

SQLiteOpenHelper dbHelper = new MySqliteHelper(this);
SQLiteDatabase db = dbHelper.getWritableDatabase();

  private void createTable(SQLiteDatabase db){
    //SQL语句
    String sql = 
    "create table stutable(_id integer primary key autoincrement,name text,age integer)";
    db.execSQL(sql);
  }

  //SQLiteDatabase类中提供的方法
  public long insert(
     String table,//要操作表名 
     String nullColumnHack,//空列的默认值 
     ContentValues values
//ContentValues封装了列名称和列值的Map
     ); 

  private void insertToTable(SQLiteDatabase db){
    ContentValues cv = new ContentValues();
    cv.put("name","wxq");
    cv.put("age",11);
    db.insert("stutable",null,cv); 
  }

  //SQLiteDatabase类中提供的方法
  public int delete(
      String table,//表名称
      String whereClause,//删除条件
      String[] whereArgs); //删除条件值数组

  private void deleteToTable(SQLiteDatabase db){
    //删除条件,这里以name为条件，也可以是age = ?
    String whereClasuse = "name = ?";
    //删除条件参数,
    String[] whereArgs = new String[]{"wxq"};
    //执行删除
    db.delete("stutable",whereClasuse,whereArgs);
  }

  //SQLiteDatabase类中提供的方法
  public int update(
  //表名称
  String table,
  //和行列ContentValues键值对应的key-value
  ContentValues values,
  //更新条件
  String whereClause,
  //更新条件数组
  String[] whereArgs
  );

  private void updateToTable(SQLiteDatabase db){
    //实例化ContentValues
    ContentValues cv= new ContentValues();
    cv.put("age",23);
    //更新条件
    String whereClause = "name = ?";
    //更新条件数组
    String[] whereArgs = new String[]{"wxq"};
    db.update("stutable",cv,whereClause,whereArgs);
  }

  public Cursor rawQuery(
  String sql,//查询的SQL语句
  String[] selectionArgs//当SQL语句中含有?,这里代表值
  );

  public void queryToTable(SQLiteDatabase db){
    String sql = "select * from stutable";//全查
    Cursor c = db.rawQuery(sql,null);//这里会返回一个Cursor(游标)对象
  }

public class HeroSqliteManager {
  private SQLiteOpenHelper dbHelper;
  private SQLiteDatabase db;
  private static HeroSqliteManager instance;

  private static final String TABLE_NAME = "hero";
  private static final String NAME_FIELD = "name";
  private static final String ICOID_FIELD = "icoId";
  private static final String ATTACK_FIELD = "attack";
  private static final String DEFENSE_FIELD = "defense";

  public static HeroSqliteManager getInstance() {
    if (instance == null) {
      synchronized (HeroSqliteManager.class) {
        if (instance == null) {
          instance = new HeroSqliteManager();
        }
      }
    }
    return instance;
  }

  private HeroSqliteManager() {
    dbHelper = new HeroSqliteHelper(HeroApplication.getContext());
    db = dbHelper.getWritableDatabase();
  }

  /**
   * 插入记录
   * @param hero
   */
  public void insertData(Hero hero) {
    ContentValues cv = new ContentValues();
    cv.put(NAME_FIELD, hero.name);
    cv.put(ICOID_FIELD, hero.icoId);
    cv.put(ATTACK_FIELD, hero.attack);
    cv.put(DEFENSE_FIELD, hero.defense);
    db.insert(TABLE_NAME, null, cv);
  }

  /**
   * 删除记录
   * @param
   */
  public void deleteData(int id) {
    String whereClasuse = "_id = ?";
    String[] whereArgs = new String[]{String.valueOf(id)};
    db.delete(TABLE_NAME, whereClasuse, whereArgs);
  }

  /**
   * 修改记录
   * @param hero
   */
  public void updateData(Hero hero) {
    ContentValues cv = new ContentValues();
    cv.put(NAME_FIELD, hero.name);
    cv.put(ICOID_FIELD, hero.icoId);
    cv.put(ATTACK_FIELD, hero.attack);
    cv.put(DEFENSE_FIELD, hero.defense);
    String whereClasuse = "_id = ?";
    String[] whereArgs = new String[]{String.valueOf(hero.id)};
    db.update(TABLE_NAME, cv, whereClasuse, whereArgs);
  }


  /**
   * 查询所有的英雄
   * @return
   */
  public List<Hero> selectData() {
    List<Hero> heroList = new ArrayList<>();
    Cursor c = db.rawQuery("select * from " + TABLE_NAME, null);
    while (c.moveToNext()) {
      Hero hero = new Hero();
      hero.id = c.getInt(c.getColumnIndex("_id"));
      hero.name = c.getString(c.getColumnIndex(NAME_FIELD));
      hero.icoId = c.getInt(c.getColumnIndex(ICOID_FIELD));
      hero.attack = c.getInt(c.getColumnIndex(ATTACK_FIELD));
      hero.defense = c.getInt(c.getColumnIndex(DEFENSE_FIELD));
      heroList.add(hero);
    }
    c.close();
    return heroList;
  }

  /**
   * 按name查询
   * @param name
   * @return
   */
  public Hero selectForName(String name) {
    Cursor c = db.rawQuery("select * from " + TABLE_NAME + " where name = ?", new String[]{name});
    Hero hero = null;
    if (c.moveToNext()) {
      hero = new Hero();
      hero.id = c.getInt(c.getColumnIndex("_id"));
      hero.name = c.getString(c.getColumnIndex(NAME_FIELD));
      hero.icoId = c.getInt(c.getColumnIndex(ICOID_FIELD));
      hero.attack = c.getInt(c.getColumnIndex(ATTACK_FIELD));
      hero.defense = c.getInt(c.getColumnIndex(DEFENSE_FIELD));
    }
    c.close();
    return hero;
  }

  public void destroy() {
//    if (db != null) {
//      db.close();
//    }
//    db = null;
  }
}